[NFC] OptimizeAddedConstants: Early exit if there are no memories (#6926)

The pass optimizes loads and stores, so without a memory there is nothing to
do.

This only helps if the user set --low-memory-unused and also has no memory,
which is likely rare, but it's a trivial change so it seems worthwhile. In particular
this pass constructs a LocalGraph, so if we can avoid work it can be substantial.

1 files changed, 5 insertions, 0 deletions

diff --git a/src/passes/OptimizeAddedConstants.cpp b/src/passes/OptimizeAddedConstants.cpp
index c76711d8a..f03109223 100644
--- a/src/passes/OptimizeAddedConstants.cpp
+++ b/src/passes/OptimizeAddedConstants.cpp
@@ -290,6 +290,11 @@ struct OptimizeAddedConstants
               << "--low-memory-unused flag is set.";
     }
 
+    if (getModule()->memories.empty()) {
+      // There can be no loads and stores without a memory.
+      return;
+    }
+
     // Multiple passes may be needed if we have x + 4 + 8 etc. (nested structs
     // in C can cause this, but it's rare). Note that we only need that for the
     // propagation case (as 4 + 8 would be optimized directly if it were